Vacuum producing apparatus for paper making machines



E. POIRIER 3 VACUUM PRODUCING APPARATUS FORFAPER MAKI/NLG MACHfNES Nov 25;, 1941 Filed May 6, 1957 I INVENTOJ? A ATTORNEY.

. uum boxes.

Patented Nov. 25, 1941 UNITED STATES PA EN LOFFICE] 1 VACUUM rsonncmc arrm'rus Fon PAPER. MAKING moms Ernest Poirier, Watervillg Maine v 1 Application my 6, 1937, Serial No. 141,104 I l2 blaims.

In a Fourdrinier paper machine thepaper making wire, together with the wet web oi paper being formed on it is run over a series of vac- Subsequently, the web is delivered to the couch roll and is then taken of! the wire. In most installations the vacuum is maintained in the boxes by means a vacuum puma-but where circumstances permit, it is also occasionally a practice to equip each box with a drop leg which carries away the water discharged by the box, and this discharge of water is depended upon to create the working vacuum in the box. Ina typical arrangement the lower ends of the drop legs are located in a well into which the water is delivered and which seals the ends of useful.

The nature of the invention-will be readily un-' derstood from the following description when accordingly, the term vacuum box? will behere- I c in used in a generic sense toinclude vacuum rolls and similar devices with which the invention is read in connection with the accompanying drawing, and the novel features will be particularly pointed out in the appended claims. In the drawing,

Figure 1 is a side elevation,

bodying the present invention;

the legs, the surplus water either overflowing into a river, or being taken out of the wellby a pump.

The drop leg arrangement has the advantage of being more economical both in initial cost and in operation than the vacuum. pump installation. A serious objection to it, however, is the fact that the degree of vacuum produced in the boxes varies greatly with the amount of water discharged from them. For example, if the paper being manufactured at a given time is of a 'very porous nature, such as a news sheet, and the sheet begins to run denser, or a change is made to a denser type of paper, the change in characteristics of the sheet will effect a reduction in the flow of air through the sheet and will prevent as free an extraction of water from it at a given vacuum as in the formercase. At the same time a higher degree of vacuum really is required by the denser sheet, but the smaller quantity of water extracted by and discharged from any individual box over which itis passing tends to create a lower degree'oi vacuum in that box. While the machine tender can make changes in the delivery of the stock and in its consistency, which will produce satisfactory con- 7 ditions for operation on the denser sheet, it is evident\ that these changes and adjustments necessarily require a high degree of skill and very close attention on his part.

e The present invention relates to apparatus "of this general type, and it aims to improve equipment of this character wi h a view to 'maintain-.

ing autofitically vacuum con tions in the boxes suitable for the characteristics of the sheet being produced and to reduce the care, skill and attention required on the part 01 the machine tender while still obtaining the advantagesot the drop leg arrangement.

4 Fig. 2 is a vertical, sectional view through the upper portion of V 1; and

one oi the valves shownin Fig.

parts in eleva- Referring flrstgto Fig. 1, the apparatus there shown comprises a vacuum box 2, like those commonly used in Fourdrlnier machines, the paper making wire running over the top of the box.

Fig. 3 is a sectional view, with tion, showing amodification.

Usually several of these boxes are arrangedside I by side so thatthe wire runs over them succcessively. Also, as in the usual constrfuctions, the box 2 is equipped with a sliding head 3. adjustable in accordance with the width of the sheet being made. From the left-hand end of. the box a shortpipe connection 4 is located to carry away the water extracted from the sheet, this connec-- tion being: equipped with a hand operated valve 5 so that any selected number of the entire series of boxes can be cut into or out of operation, as

desired. All of the foregoing is substantially like the usual constructions. According to the present invention the discharge pipe 4 leading from-the vacuum box is connected to the intake end ofa vacuum casing 6 of a novel form and a drop leg, indicated in general at 1, leads downwardly from this casing. This leg consists of several independent sections 7 or conduits, thenumber of-which necessarily will vary somewhat with the requirements of diii'erent installations. In the particular arrangement shown three of these sections or conduits are employed indicated, respectively, at a, b and c. The lower end of the drop leg is located inone compartmentof a well or overflow-box 8 equipped with the usual adjustable weirlil, over which the water flows from the compartment in which the ends 01' the drop'legs are located into another compartment from which the water is taken away by a pump (not shown) which is connected to the box 8 by the pipe It. In some cases the water overflowing the weir l0 flows directly into theriver. Preferably a vacuum gage I3 is connected into the casing 8 to indicate constantly to the operator the degree oivacuum maintained when the machine isin operation water is largely diagram- 7 matic in character, illustrating an apparatus emextracted from the travelling web of paper by the box 2, and this water is discharged through the pipe 4, vacuum casing 6 and drop leg I, thus creating a vacuum in the box, which vacuum is utilized for normal operating purposes. The degree of vacuum so maintained is determined fundamentally by the head ofwater in the drop leg which, in turn, depends partly upon the volume of water discharged from the box," partly on the volume of air,flowing through the sheet of paper passing over the box, and in some measure, also, on the rate of release of the air entrained with the water as it flows through the drop leg and is discharged. If the character of the sheet. being made is such that the volume of water is small, it will not be able to fill a large drop leg to -the same height as it would a small leg.- Consequently, if the volume of air. leaking through the sheet remains constant while the volume of water decreases,- the vacuum in the box will also decrease, other conditions being equal. On the other hand, if the volume of water should increase, the degree of vacuum would rise, provided other conditions remain 'unchanged. Of course conditions such as those just described rarely, if ever, will happen in the actual operation of a paper machine because an increase in the volume of water delivered toany individual box practically always means that a more porous or freer sheet is passing over the boxywhereas a reduction in water usually accompanies the formation of a lessporous or slower sheet.

,I have found that variations inthe degree of vacuum produced by such changes in conditions as those Just described can be by making the drop leg in. sections somewhat as shown. In the particular instance illustrated it maybe assumed, for example, that the sections a and I! each consist of twoinch pipes, whereas greatly reduced x such an increase. Upon will be brought into operation automatically by a decrease in volume of water the drop leg sections actually in operation will decrease successively, only those remaining in operation at any time which are necessary to conduct the volume of water being used at that time.

In this connection it may also be pointed out 'thatwhen, for example, the character of the preferably, a valve of that sheet changes from a free to a slow sheet with a corresponding reduction in the volume of water extracted by the box, the fact that the top of the .box then is sealed more effectively by the sheet, due to its, higher density, and consequent reduction in the volume of air leaking through it, tends to increase the degree of vacuum produced by the flow of a given volume of water through the drop leg. This is a helpful factor at a time when a higher vacuum is needed. A

reverse action occurswhen a freer sheet is being run.

In order to provide a further increase in vacuum when it is needed, as for-example, in starting up, or at any other time, I prefer to run another .vacuum line ll into the casing" 6 from any convenient supplemental source of vacuum pressure as, for example. to the vacuum line it running to the couch roll. It is sometimes desirable to include a valve 11 in thisline which may either be a gravity check valve or, more general nature in which the movable valve-element is, backed up by a spring which can be adjusted, the valve in either event permitting a flow from the casing 6 toward the vacuumheader It but preventing f how in the opposite direction. This valve may be set to open whenever the'vacuum in the casing the section c consists of a four inch pipe. If

- now the volume of water is'so reduced that the pipe it carries it all, then the degree of vacuum maintained in the casing 0 will be held at a higher value than it would if this pipe were, say, six inches in diameter for the reason that the head of water maintained in it wouldbe considerably higher in the former case than in the latter. And, as above pointed out, thismatter r of hydraulic head-is an extremely important factor in determining the degree .of vacuum that will be maintained in the casing at any instant.

Preferably baiilesll, Fig. 1, are provided in the bottom of the casing 6, dividing this part of the easing into three compartments from. which the respective sections of the drop leg lead. These bafiles assist in controlling the flow of water, di-' recting a small flow almost exclusively into the section a, and when the first baflie is overflowed, preventing any substantial flow into the compartment farthest from the pipe connection 4 I until the head of water in thecasing has risen so that both baifles are submerged.

From the foregoing it will be evident that with this arrangement the number of sections of the drop leg which are utilized at any instant to carry away the water from the box I will change automatically with changes in the volume of water discharged from the box. In other words, when the volume is so small that a single section of the drop leg will take care of it, then pracexcessively small with Fig. 1, is lead through linelies in the bottom of the intake pipe l. Here it is contemplated that the'pipe I! always will line It. Thus it creates a vacuum in the case i and box 2 during the starting period and increases the vacuum in these members whenever it falls below substantially a predetermined value for any reason.

Preferably the tip d, Fig. 1, of the vacuum pipe i5 is turned at an angle to the main portion of the pipe and is connected with the valve l|- "through a coupling l8. Thus this. tip can be adjusted so that its open end will practically always be above the level ofthe water'in the casing 5. a

In another arrangement shown in Fig. 3, the pipe'i5', corresponding to the pipe I! shown in the casing 6 and its inner be open to the suction line. Normally, however, this pipe will be submerged in water. It is made relatively small say. for example, a one inch pipe, and consequently, the volume of water which .canbe carriedh'f! through it is relatively small. However, if the flow of water becomes the consequent tendency to reduce the vacuum, the add the pipe I! ticallyall of the discharge will take place through that section. As soon, however, as the volume of water increases beyondthe capacity of the iirst section, one or more of the other sections then will be more orlessopen, thus permitting a relatively large flow of air through the pipe (since it will conduct a larger volume of air than water at agiven vacuum) with a resultant increase in the degree of vacuum maintained in the casing 8. By making this pipe with an angularly disposed tip as .shown at d, in Fig. 1,

its intake end can be adjusted into different levels." Thus the control of the flow of air, water, or mixtures of these fluids through this pipe, which isaflorded by the relation of said intake pump, it is desirable to mount a float controlled shut-oil device, such as that shown at 30 in Fig.

1, where it will close the end of the pipe in the inlet ports 2| and also includes a valve plunger 22 and a spring 23 acting on said plunger and tending to hold it in contact with a yielding stop 24. Whenagainst said stop it cooperates with a circular seat 25 to prevent any substantial flow of air from the ports 2! into the interior -of the valve. The outer surface of the valve,

however, is constantly subjected to atmospheric pressure, and the effect of this pressure on the plunger 22 is opposed by such fluid pressure as there may be inside the valve chamber, plus that of the spring 23. Normally this valve plunger simply floats-between these two pressures and is moving almost constantly when the machine is admit air into the interior thereof and thence into the box 2 through pipe connections '26 therewith, thus relieving the vacuum. These pipe connections should be made very short so that the eflect of any change of vacuum in the box is felt as promptly as possible by the valve plunger 22. Such connections, however, should open into the box 2 at such a point that it will communicate with the interior of the box regardless of the adjustment of the head 3, but preferably also at a point remote from the discharge end 4. The pressure at which, this valve will respond can be adjusted either by screwing the casing 20 up or down on its supporting nipple 21, orby connecting it with the box through an ordinary valve 28 so that this valve can be adjusted by. hand to throttle the flow of air through it more or less.

This valve, when connected with the-b011 2,

approximately as shown, operates in conjunction r with the sectional drop leg arrangement to pro duce an exceptionally uniform degree of vacuum in the box. This is highly desirable in thei-operation of a Fourdrinier paper machine, as'is well understood by those skilled in this art-,variations in the degree of -vacuum having,.-an important sheet, whereas a constant vacuum is a great help in producing a uniformsheet. In addition to maintaining a higher'hydrostatic head in a drop leg, constructed as'above described, during. those periods whenthe supply of water is small, than and undesirable effecton the form'ation of the would be, possible in a drop leg consisting of a single pipe of equivalent cross-sectional area, this divided leg arrangement is also of advantage in reducing the rate of separation of the entrained air from the water as compared with that which would occur in the larger leg. The higher head naturally creates a greater 'velocity of flow through the small section utilized than would occur through a large pipe or conduit. Consequently, the entrained air has less opportunity to escape from the water. This factor also is of advantagein producing a higher vacuum in the box during periods of low rates of water discharge than would be obtained with the customary arrangement.

When the water discharged into the overflow 7 box 8 is carried away from it by means of a event that the compartment from which it draws water becomes substantially empty. Normally the float 3| holds the shut-oil plate in an elevated position andleaves the intake end of the pipe l2 completely open, but if the pump takes the water so much faster than it is delivered to the supply compartment of the box 8 as to empty the outlet compartment, the plate 3| will substantially close the intake end of the pipe before this occurs and it thus aids in preventing the pump from becoming air bound. Usually such a condition shortly corrects itself. a

While a single vacuum box has been shown in the drawing, it will be understood that a series of these boxes customarily is used, as above detypical embodiment of my invention, it will be understood that this disclosure has been made rather by way of explanation than limitation, and that the invention may be embodied in other forms without departing from the spirit or scope thereof.

Having thus described my invention, what I desire to claim as new is:

1. In an apparatus for'extracting water from a travelling web of paper or the, like, the combination with a vacuum box over which the web runs in water extracting relationship thereto, of a vacuum casing communicating withsaid box and into which the water extractedby the box is delivered, said casing being divided into a plurality of compartmentaa drop leg leading downwardly from said casing, said leg being composed of a plurality of conduits communicating with said compartments and so arranged that the number of conduits utilized at any time to carry the water away from said'box will automatically change with changes in the volume of water discharged by the box and means for sealing the lower end of said drop, leg.

2. In an apparatus for extracting water from a travelling web of paper or the like, the combination with a vacuum box over which the web runs in water extracting relationship thereto, of a vacuum casing communicating with said box and into which the water extracted by the box is delivered, means dividing the casing into a plurality of compartments, a drop leg leading downwardly from said casing, said leg being composed of a plurality of conduits communicating with said compartments, the upper ends of said con-- duits being so arranged that successive conduits will automatically receive water from said box in accordance with variations in the volume of water discharged by the box and means for sealing the lower end of. said drop leg.

3. In an apparatusfor extracting water from plurality of compartments, a drop leg leading downwardly from said casing, said leg being composed of a plurality of independent conduits communicating with the compartments and so arranged that the number of said conduits utilized at any time to carry the water away from said box will be automatically reduced by a-substantial reduction in the volume of water discharged irom the box'and will be automatically increasedby a substantial increase in the volume 01' water so discharged and meansior sealing the lower end of said drop leg.

4. In an apparatus for extracting water from a travelling web of paper or the like, the combination with a vacuum box over whichthe web runs in water extracting relationship thereto,

a vacuum casing communicating with and closely adjacent to said boxrand into which the water extracted by the box is delivered, means dividing said casing into a plurality of compartments, a

- and, other conduits will be brought into operation automatically by a substantialincrease in the head of water in said casing and means for v sealing the lower end of said drop leg.

5. An apparatus according to preceding claim 1, in which the lower partoi said casing is diin accordance with iiuid conditions in said casing and means for sealing the lower end of said drop 9.-In an apparatus 'ior extracting water from a travelling web of paper or the like, the combination with a vacuum box overwhich the web runs in water extracting relationship thereto, 01 a vacuum casing communicating with and closely adjacent to said box and into which the water' extracted by-the box is'delivered, said casing beingdivided into a plurality of compartments,

and a drop leg. leading downwardly from said casing, said leg being composed of a plurality of conduits communicating with said compartments and so arranged that the number of them utilized at any time to carry the water away from said box will automatically change with substantial changes in'the volume oi water discharged by the box, a} supplemental vacuum line leading into saidcasing, the end of said 'pipe'being located with reference to the normal level of water videdinto compartments from which said respective conduits, of the drop leg lead andsaid compartments are spaced at different distances in water extracting relationship thereto, or

from the point of delivery oi'the water tosaid' box.

said box at a point remote from its water discharging end and arranged to open automaticallyto admit air to said box when thevacuum inthe casing tocause changes in said level to control'the flow oi fluid irom'said casing through said line and means-tor sealing the lower end 0! said drop leg. 10. In'an apparatus for extracting water from a travelling web oi'fipaper or the like, the combination with a vacuum box over'which the web a vacuum casingcommunicating with said box and lntowhlch the water extracted by the box therein exceeds a substantially predetermined limit;

7. In an apparatus for extracting water i'rorn I a travelling web of paper or the like, the combi-.

nation with a, vacuum box over which the web runs in water extracting relationship thereto, 01

a vacuum casingcommunicating with and closely adjacent to said box and into which the water extracted by the box is delivered, said casing being divided into a plurality of compartments,

tial changes in the volume of water discharged by the box, additional means for automatically increasing the degree of vacuum in said box when said drop leg apparatustails to maintain the desired degree of vacuum therein and means for sealing the lower end 01' said drop leg.

8. In an apparatus for extractingwater from a travelling web of paper or the like, the combi- V nation with a vacuum box over which the web runs inwater extracting relationship thereto, of

a vacuum casing communicating with and closely adjacent to said box and into which, the water said box will automatically change with substanextracted by the box is delivered, said casing being divided into a plurality of compartments, and a drop leg leading downwardly from said i casing, said leg being composed of a plurality of conduits communicating with said'compartments and so arranged that the number or themutilized at any time to carry the water away from tial changes in the volume of water discharged by the box, a supplemental vacuum line leading into said casing, meansin said line for automatically controlling the flow of fluid therethrough said box will automatically change with substan-' is delivered. said casing being divided into a pluralityoi compartments, a drop leg leading downwardly from said casing, said leg being composed oi'a plurality of conduits communicating with said compartments, means cooperating with said conduits to control the ilow of water to them to vary automatically the'number of said conduits utilized in accordance with'the volume of water discharged by the box and means for sealing the' lower end of said drop leg.

11. In anapparatus for extracting water from a travelling web of paper or the like, the combination with a' vacuum box over which the web in water extracting-relationship thereto, 0! a vacuum casing communicating with said box and into which the water extracted bythe box is delivered, bai'fles dividing-said casing into a plurality or compartments, a drop leg leading downwardly from said casing, said leg being composed 1 01. a plurality of conduits, said baflles serving to distribute'automatically the water to the conduits in a manner depending upon the number of them required to handle the volume of water discharged by the box and means for sealing the lower end of said drop leg.

12. In an apparatus for extracting water from I a travelling web oi paper or the like, the combination with a vacuum box over which the web runs in water extracting relationship thereto, of a vacuum casing communicating with said box and into 'whichthe water extracted by the box is delivered, said casing'being dividedinto a plua vacuum line opening into said casing and means iorsealing the lower end oi said drop leg.

' manner Ponuaa. 

